Corrugation punch press



May 16, 1967 ET W|$H ET AL 3,319,452

CORRUGATION PUNCH PRES 5 Filed Oct. 7, 1963 3 Sheets-Sheet 2 4 FIG. 3

33 FIG. 4 U r (/20 23 a5 22 FIG. 9 u

m "N W I w E m FIG. 7 FIG. 8 BY HARDIN ATTORNEY May 16, 1967 E HM H ETAL 3,319,452

CORRUGATION PUNCH PRESS 3 Sheets-:Sheet 5 Filed Oct. 7, 1963 INVENTORS.W. F. RETHWISH D S HARDING ATTORNEY United States Patent Ofifice3,319,452 Patented May 16, 1967 3,319,452 CORRUGATIGN PUNCH PRES WilliamF. Rethwish, National City, and Dale S. Harding, Chuia Vista, Califi,assignors to Ruhr Corporation, Chula Vista, Calitl, a corporation ofCalifornia Filed Oct. 7, 1963, Ser. No. 314,191 14 Claims. (Ci. 72-397)This invention relates generally to machines for fabricating honeycombcore and more particularly to a corrugation punch press for formingcorrugations in the metallic ribbon used in the fabrication of thehoneycomb core.

In a core fabricating machine such as disclosed in Patent No. 3,079,487,issued to F. H. Rohr for Method and Apparatus for Fabricating HoneycombCore, a corrugated metallic ribbon is folded back and forth upon itselfto form the successive layers of the core. In order to form quality highstrength core in this manner, it is necessary that the corrugations inthe ribbon be precisely formed and coined without introducingappreciable distortion or strain into the ribbon material during thecorrugation process. This is imperative in order that the corrugatedribbon will have the same spacing from node to node such that the nodesof the confronting ribbon layers will be aligned and abutted preparatoryto the resistance welding of the nodes together to form the cells of thecore. As disclosed in the aforesaid patent, wherein provision is madefor programming the corrugated ribbon of successive sections ofdifferent thickness to provide a core of predetermined structuralpattern and density, it is equally important that the corrugationconfiguration and nodal spacing be precisely maintained since theseparameters provide the reference datum in determining points in thefabricated core at which changes in density are to occur in accordancewith the predetermined pattern.

Various corrugation methods have heretofore been employed such, forexample, as for passing the flat ribbon through a pair of corrugatinggears, as disclosed in Patent No. 2,843,722 issued to Milton G.Wegefo-rth for Apparatus and System for Producing Honeycomb Core. Thismethod, however, has not been found to be entirely satis factory in theproduction of high quality metallic core for the reason that the meshinggears tend to form several corrugations at a time therebetween, and theribbon which must be drawn from the supply to form these corrugations,becomes unduly stretched and strained in the cor rugation process. Thegears, moreover, do not coin the corrugations, that is they do not formsharp bends and give a permanent set to the ribbon such that it becomesprecisely formed and spaced from node to node.

Corrugation punch presses of the type disclosed in the aforesaid patentof Fred H. Ro-hr provide the required coining of the metallic ribbon asthe corrugations are formed, but have not entirely solved the problem ofminimizing the stresses and strains due to the drawing and inordinateworking of the ribbon as the corrugations are formed, even where, as inthe aforesaid case stages of spring loaded corrugation punches are usedin the operation.

In accordance with the arrangement of the corrugation punch press of thepresent invention, upper and lower corrugating dies, respectively havedifferentially spring loaded die members, cooperate during the initialclosing of the dies to yieldably clamp and hold a previously formed,substantially V-shaped ribbon corrugation between the spring loadedmembers and, thereafter, as the die-s continue to close, to brake theunformed ribbon therebetween in two steps, to thus form the twosidewalls of a new corrugation, as the holding die members bottom insuccessive order, after which the dies, together and as a unit withtheir holding die members, forcibly move together to coin the newlyformed corrugation therebetween. In this operation, the braking actioninvolves essentially a translatory swinging movement of the unformedribbon portions about certain of the tooth edges of the dies which actas pivotal points. The result of this action is that the necessarydrawing of the ribbon from the storage reel is due essentially to thebraking action. and such working of the ribbon material as may occur inthe corrugation process, is thus held to a minimum, to thussubstantially prevent the introduction of stresses and strains into thecorrugated ribbon. As will become more fully apparent as the descriptionproceeds, certain nodal portions of the ribbon experience no working ofthe metal at all, save for the ultimate coining which is de sired; thenodal portions merely being translated, as required, in the corrugationprocess to place the nodes alternately at the peaks and valleys of thecorrugated ribbon.

An object of this invention is to provide a new and improved corrugationpress for corrugating metallic ribbon which affords all of theadvantages of prior corrugators while substantially obviating thedifiieulties thereof.

Another object is to provide a corrugation press which elfectivelybrakes an unformed ribbon in successive steps to form a new corrugationand finally coins the same as the press closes.

Still another object is to provide a corrugation press which utilizesdifferentially biased die members to brake successive unformed portionsof a ribbon to form a new corrugation therefrom as the die members moveto bottom in successive order.

Yet another object resides in the provision of a corrugation die presswherein differentially biased holding die members initially move toclamp a previously formed ribbon corrugation therebetween, wherein theholding member having the greater bias serves as an anvil to bra-ice afirst portion of the unformed ribbon thereon as the lesser biased membermoves to bottom on its die and wherein the greater biased member movesto bottom on its die as a second portion of the unformed ribbon brakesbetween the dies.

An additional object is to provide a corrugation press in which thedrawing of the rib-bon required to form a new ribbon corrugation is dueessentially to the braking of successive portions of the unformedribbon.

Still other objects, features and advantages of the present inventionare those inherent in or to be implied rom the novel constructioncombination, and arrangement of parts of the preferred embodiment of theinvention, hereinafter to be described, which has been constructed inaccordance with the best mode thus far devised for practicing theprinciples of the invention. In the accompanying drawings which disclosethis preferred embodiment:

FIG. 1 is a view in elevation of the corrugation press of the presentinvention;

FIG. 2 is a view from the under side of the upper die of the corrugationpress as viewed along line 2-2 of FIG. 1 and rotated counterclockwisefrom the position of FIG. 1;

FIG. 3 is an enlarged view of the upper die of FIG. 2;

FIG. 4 is a sectional view taken along the line 4-4 of I Referring nowto the drawings for a more complete understanding of the invention, andfirst more particularly to FIGS. 1 and 2 thereof, and 11 designate fixedand movable die supports which, in practice, may be referred to asshoes, but for purposes herein, conveniently may be considered as theanvil 10 and the ram or punch 11 of a conventional punch press. Support11 is normally positioned above fixed support 10 and is slidably mountedon the upstanding and suitably spaced cylindrical guides 13 and 14 formovement forcibly toward and away from the fixed support. For thispurpose, guides 13 and 14 are suitably secured to fixed support 10, andmovable support 11 is suitably driven from a power source acting throughits coupling member 12. Hubs 15 and 16 on support 11 extend the bearingsurface afforded thereby on guides 13 and 14. Hubs 15 and 16 and guides13 and 14 are disposed concentrically with respect to semicylindricallateral extensions 17 and 18 of support 11.

A die set comprising dies generally designated 19 and 20, respectively,are suitably secured to the fixed and movable supports 10 and 11, as byscrews 21, FIG. 2, which preferably are seated in countersunk openings22. Dies 19 and 20 are generally similar, and the same referencecharacters therefore, will be applied to the same or like elements ofthese dies throughout the several views.

Each of dies 19 and 20 comprises a forming die member 23 having onetooth 24, anda relatively movable holding die member 25 having two teeth26, Die members 23 and 25 for both dies 19 and 20 are identical andtheir opposing teeth 24 and 26 complement each other such that the sameintermesh as depicted in FIGS. 1 and 7 to 9. The line of engagementbetween the teeth also depicts the corrugation configuration to beimparted to a metallic ribbon 27 interposed therebetween, as depicted inFIGS. 6 to 9. As may be seen from this configuration, the resultingcorrugations in the ribbon will be generally V-shaped with flattenedsurfaces or welding nodes 28 and 29 respectively provided at the crestsand valleys of corrugated ribbon.

Referring now more particularly to FIGS. 1 to 4, it will be seen thateach forming die member 23 is secured at the ends thereof, as bycountersunk screws 30, to a pair of end plates 31 which, in turn, aresecured by countersunk screws 32 to the die guide block and mountingmember 33. Member 33 has a mounting flange 34 which carries theaforementioned screws 21 for mounting dies 19 and 20 on their respectivesupports 10 and 11. End plates 31 also carry screws 21 which servefurther for this purpose.

Die members 23, 31 and 33 when assembled and se cured together, asaforedescribed, provide a guide channel 35, FIG. 4, for the holding diemember 25 which is provided with a flange or shoulder 36. Guide channel35 is appropriately widened at 37 to accommodate the shoulder and alsoprovide a seat therefor to limit the movement of holding die member 25forwardly or outwardly with respect to the forming or corrugating diemember 23, as depicted in FIG. 4. It will be noted that the widenedchannel 37 has a greater length than that of the shoulder thereby topermit limited relative movement between the die members 23 and 25.Thus, when each die 19, 20 is mounted in position on its respectivesupport 10, 11, die member 25 for each die is limited in its movement inthe opposite direction as the shoulder engages the mounting surface ofits associated support, as may best be seen in FIGS. 1 and 9 wherein thedies 19 and 21) are shown to be closed and the die members 25, in suchcase, are properly shown to be bottomed on their respective supports.When die members 25 are thus bottomed, they effectively become a unitwith their respective corrugator die members 23, and teeth 26 of eachmember 25 effectively act as a unitary tooth structure with theirassociated tooth 24. This is important in the precision forming ofcorrugations in metallic materials such as stainless steels wherein itis desired to coin the formed corrugations in the final blow impartedthereto by the punch press in the instant of closing of the dies on theribbon interposed therebetween.

Holding die members 25, as may best be seen in FIGS. 5 and 6, are springloaded, as by coil springs 38, so as to be normally extended yieldablyoutwardly or forwardly of their respective forming die members 23, thesemembers being sufficiently elongated, as required, to corrugate ribbonsof various widths. A plurality of springs are employed for each diemember, and a socket 39 is provided therein for seating each spring 38.Similarly, supports 10 and 11, are provided with sockets 41 which alsoserve to seat the springs, sockets 40 being aligned with andcomplementing the sockets 39 of the die members 25.

For reasons which will become more fully apparent as the descriptionproceeds, die members 25 are differentially spring loaded, the springloading of die member 25 of die 19 being made greater than that ofmember 25 of die 21 as depicted in FIG. 5, by using two more springs 38for die 19.

It will be understood that whereas differential spring loading has beenparticularly disclosed herein, the differential bias and yieldableurging of the holding die members 25 may be accomplished by other meanssuch, for example, as by using air pressure.

With the parts positioned as disclosed in FIG. 6, the punch press isabout to begin a new cycle of operations to form a new corrugation inribbon 27, the ribbon having been just previously advanced onecorrugation by sliding over the teeth 26 of the lower holding die member25. The ribbon preferably is advanced relative to the dies, asaforedescribed, by a hitch feed mechanism such as disclosed and claimedin the copending application of Elbert M. Lacey, Jr., for Method andApparatus for Feeding Metal Strips, now Patent 3,123,125, Ser. No.78,720, filed December 27, 1960.

With ribbon 27 thus seated on the lower die member 25, the opposingmember 25 first engages the ribbon during the initial closing of die 20toward die 19, the ribbon then being clamped yieldably between the upperand lower ribbon holding members 25, as depicted in FIG. 7, at whichtime the forming of the first portion of a new corrugation is about tobegin. As die 20 continues to move toward die 19, the. same movesrelative to its holding die member 25 which cannot move at this timebecause of the greater spring force acting on the lower holder member 25which does not move until after the upper die member 25 has bottomed onsupport 11.

During this relative movement of die member 23 with respect to itsholding die member 25, a first unformed portion 41, FIG. 7, of ribbon27, corresponding to one side of a new corrugation, is formed betweentooth 24 of die 20 and the confronting tooth 26 of die 19 as the diestake the position as shown in FIG. 8.

Members 23 and 25 of die 20 now move as a unit to thus move holdingmember 25 of die 19 yieldably against its opposing spring force untilthe same bottoms on support 10, as disclosed in FIG. 9. During thismovement, a second un formed portion 42, FIG. 8, of ribbon 27,corresponding to the remaining sidewall of the new corrugation, isformed between the confronting teeth 24 of the opposing corrugating diemembers 23. In the position of FIG. 9, both die members 25 beingbottomed, the

newly formed corrugation is coined in the instant of forcible closing ofdie 20 on die 19.

Referring now more particularly to FIGS. 10a to c, for a more detaileddiscussion of the metal working aspects involved in the forming of thenew corrugation from ribbon 27, as aforedescribed, it will be seen thatthe unformed ribbon portion 41, which has a length A corresponding tothe sidewall of the corrugations to be formed, bears critically at P1 ontooth 26 of holding die member .25 of die 19, and also bears criticallyat P2 on tooth 24 of forming die member 23 of die 20. As the dies closeand the forming occurs, ribbon portion 41 brakes about the point P1 inresponse to pressure applied at the point P2. It will be appreciatedthat the ribbon slides for a small distance over the point P2 of tooth24 until the same reaches the position of FIG. b. In the braking actionof the unformed ribbon portion 41, the end of the same follows thecircular path about point P1 indicated by the dashed line 43. Thatdiminishing portion of the unformed ribbon lying between this dashedline and point P2, of course, experiences a combined sliding and brakingmovement over point P2. While a purely braking action would be ideal, noadverse effects are manifested.

A second unformed ribbon portion 42, also having a length A, brakesabout the point P3 on tooth 24 of die member 23 of die 20, as die memberof die 19 moves to bottom on support 10, and a combined sliding andbraking action of the ribbon occurs about the point P4. The brakingaction of unformed ribbon portion 42 about point P3 thus is such thatthe end of the ribbon portion follows the circular path indicated by thedashed line 44 shown in FIG. 10b.

That portion of the unformed ribbon, which lies between points P2 andP3, is designated 45 and has the nodal length B. Ribbon portion 45 issimply translated to the base of tooth 24 of die member 23 of 'die 19 asmember 25 thereof moves to bottom on the die support 10. As a practicalmatter, unformed but coined ribbon portion 45, together with ribbonportion 41, may be considered to be a first unformed ribbon portion, inthe same sense that the corresponding unformed but coined ribbon portion46, FIG. 10c, which lies between the points P4 and P5 at the closing ofthe dies, together with ribbon portion 42, may be considered to be aremaining ribbon portion, required to form a new complete corrugation,which will thus be made up of ribbon portions 41, 45, 42 and 46, as maybest, be seen in FIG. 10c.

Although the corrugation width, i.e., as measured from node to node, maybe seen to be B plus D, a length of ribbon corresponding to 2B plus 2Ais required to form a new corrugation. Of this length, as has beendescribed, there is no working of the B portions; only coining. D minusB, of course, does not equal 2A, since purely braking does not occur inthe forming of the A portions; but this is substantially the case, andthe ultimate coining of the formed ribbon in the region of points P2 andP4 removes any adverse effects which may have been introduced in theprevious working of the material as it slides over the teeth at thesepoints. In effect, the substantial length of each A portion is simplytranslated in a swinging move mentof the unformed ribbon portion aboutthe edge of one of the die teeth.

The results of a corrugation process as aforedescribed are, first,precision forming of the ribbon corrugations and, second, high qualityblocks of honeycomb core when the same are fabricated from the precisioncorrugated ribbon. Such blocks are undistorted and unwarped and haveoptimum welds at abutting nodes which are aligned consistently from nodeto node. The fabrication of cores from such ribbon desirably may beprogrammed with assurance that the corrugations will be uniform inspacing and the nodes will properly align and abut preparatory towelding of the same together.

The manner of operation of the differently biased corrugation press ofthe present invention also lends itself to the precision forming ofperforated ribbon, as more fully described in the copending applicationof Elbert M. Lacey, Jr., et al., for Method and Aparatus for Perforatingand Corrugating Metallic Ribbon, Ser. No. 329,744, filed Dec. 11, 1963,now Patent Number 3,307,384. It sufiices herein merely to state thatprotuberances formed in the ribbon upon perforation of the same aregenerally pressed and formed by the corrugation press into an eyeletconstruction which prevents incipient tearing and fracturing of theribbon in the region of the perforations.

The differentially biased corrugation press of the present inventionalso lends itself to the forming and coining of corrugations havingfluted sidewalls 47, as depicted in FIG. 11. In such case, the sidewallsof teeth 24 and 26 are correspondingly fluted.

It will be apparent from the foregoing that a corrugation press has beenprovided which is well adapted to fulfill the aforestated object of theinvention. It will be apparent, moreover, that this invention may beembodied in other forms or carried out in other ways without departingfrom the spirit or essential characteristics thereof. The presentembodiment of the invention is therefore to be considered as in allrespects illustrative and not restrictive, the scope of the inventionbeing indicated by the appended claims, and all changes which comewithin the meaning and range of equivalency of the claims are intendedto be embraced therein.

Having thus described our invention, what we claim as new and useful anddesire to secure by Letters Patent is:

1. In a punch press for precision forming of corrugations successivelyone at a time in metallic ribbon, the combination of opposing die meansrespectively comprising yieldably extended die portions for braking andforming a first unformed portion of the ribbon therebetween thereby toform only a first portion of a corrugation in the ribbon as one of thedie portions moves yieldably to bottom on its die means and for brakingand forming a second unformed portion of the ribbon thereby to form onlythe remaining portion of said corrugation as the other die portion movesyieldably to bottom on its die means.

2. In a punch press as in claim 1, said die means and the die portionsbottomed thereon being constructed and arranged for unitary closingtogether thereby to coin said formed corrugation therebetween in theinstant of closing of the die means.

3. In a punch press for precision forming of corrugations successivelyone at a time in metallic ribbon, the combination of opposing die meanshaving matching surfaces corresponding to the corrugation configurationof a ribbon to be corrugated therebetween and respectively comprisingdifferentially biased die portions for engaging and clamping apreviously formed corrugation of the ribbon, for braking a firstunformed portion of the ribbon thereby to form only a first portion of anew corrugation in the ribbon as one of the die portions moves yieldablyto bottom on its die means, and for braking a second unformed port-ionof the ribbon thereby to form only the remaining portion of said newcorrugation as the other die portion moves yieldably to bottom on itsdie means.

4. In a punch press as in claim 3, said opposing die means comprisingdie teeth having said matching surfaces, and said die teeth beingintermeshed in the instant of closing of the die means thereby to cointhe new corrugation therebetween.

5. In a punch press for precision forming of successive substantiallyV-shaped corrugations in metallic ribbon, the combination of opposingrelatively movable die means having matching surfaces corresponding tothe corrugation configuration of a ribbon to be corrugated therebetweenas the die means are closed, said die means respectively havingyieldably biased and linearly movable die portions which extend intoconfronting relation to the ribbon to clamp a previously formedcorrugation therebetween, one of said die portions being yieldablybiased to a lesser extent than the other, said die means being operableto brake a first unformed portion of the ribbon therebetween thereby toform a first one-half portion of a new V- shaped corrugation in theribbon as the lesser biased die portion moves yieldably to bottom on itsdie means, said die means being operable to brake a second unformedportion of the ribbon therebetween thereby to form the remainingone-half portion of said new corrugation as the other die portion movesyieldably to bottom on its die means, and said die means being operableas the same move relatively to closed position to coin said newcorrugation to said configuration.

6. In a punch press for precision forming of corrugations in metallicribbon, the combination of normally separated dies relatively movabletoward each other to closed position, said dies having opposing teethcorresponding in configuration to the corrugations to be formed in theribbon and movable into meshing relation as the dies move into saidclosed position, said dies each having only one fixed tooth disposed formeshing engagement with the fixed tooth of the other for forming saidcorrugations one at a time upon successive closing movements of the diesto closed position, and said dies respectively comprising differentiallyspring loaded toothed die portions which move yieldably into said meshedrelation during the initial relative movement of the dies toward eachother and yieldably move in successive order to bottom on theirrespective dies during continued relative movement of the dies to saidclosed position.

7. In a punch press as in claim 6, certain of the opposing teeth of saiddies serving to engage and clamp at least one previously formedcorrugation of the ribbon therebetween and certain other of saidopposing teeth serving to engage first and second unformed portions ofthe ribbon to form first and second portions of a new corrugationtherebetween as the die portions bottom respectively in said successiveorder.

8. In a punch press as in claim 6, one of said dies being fixed in alower position with its spring loaded die portion normally extendedupwardly of the same, the other of said dies being movably mounted forlowering movement toward said fixed die and normally having its springloaded die portion depended and extended therefrom into confrontingrelation to said upwardly extending die portion.

9. In a punch press as in claim 8, said upwardly extending die portionhaving greater spring loading than said depending die portion wherebythe same retains its upwardly extended position until said depending dieportion has bottomed on its die.

10. In a punch press as in claim 9, said die portions being engageablewith a corrugated portion of a ribbon being corrugated to clamp the sametherebetween, said fixed tooth of said movable die and a matching toothon said upwardly extending die portion having cooperating surfaces forbraking and forming there-between a first unformed portion of the ribbonto form a first portion of a new corrugation therefrom as said dependingdie portion moves yieldably to bottom on its die.

11. In a punch press as in claim 10-, said upwardly extending dieportion being driven by said movable die and its bottomed die portion tobottom in said fixed die, said fixed teeth of said movable and fixeddies having cooperating surfaces for braking and forming therebetween asecond unformed portion of the ribbon to form the remaining portion ofsaid new corrugation therefrom as said upwardly extending die portionmoves yieldably to bottom in the fixed die.

12. In a punch press for precision forming or corrugations in metallicribbon, the combination of a fixed support, a movable support mountedabove the fixed support for guided movement toward and away from saidfixed support, first and second dies respectively secured to said fixedand movable supports and having opposing teeth corresponding inconfiguration to the corrugations of a ribbon to be corrugatedtherebetween as the dies are closed, said first and second dies eachhaving only one fixed tooth disposed for meshing engagement with thefixed tooth of the other for forming said corrugations one at a timeupon successive closing movements of the dies to closed position, andsaid first and second dies respectively comprising first and secondtoothed movable die portions mounted for limited movement on theirrespective dies, said first and second die portions each having aplurality of sockets disposed in spaced relation along the lengththereof, said fixed and movable supports having a plurality of socketsrespectively complementing and aligned with those of said die portionsindividual thereto, a plurality of springs disposed in certain of thecomplementary sockets of the fixed support and said first die portionfor yieldably urging the first die portion to normally extend outwardlyfrom said first die and toward said second die, and a lesser number ofsprings disposed in certain of the complementary sockets of the movablesupport and said second die portion for yieldably urging the second dieportion to normally extend outwardly from said second die and towardsaid first die.

13. In a punch press as in claim 12, said first and second dies eachhaving a guide channel for its die portion, each said channel comprisinga main opening which extends from the toothed surface of the die and awidened portion in the region of attachment of the die to its support,each of said die portions having a shoulder disposed in the widenedportion of said channel opening in its die, and each said shoulderhaving a length less than the length of said widened portion of thechannel opening thereby to provide said limited movement of said dieportions on their respective dies.

14. In a punch press as in claim 12, said opposing teeth beingsubstantially V-shaped and each tooth being flattened at its tip and atits base and having each side wall thereof fluted.

References Cited by the Examiner UNITED STATES PATENTS 2,397,582 4/1946Watt et a1. 72397 2,510,024 5/1950 Mayer 72-397 2,847,053 8/1958 Hardman72-397 FOREIGN PATENTS 454,229 9/1936 Great Britain.

CHARLES W. LANI-IAM, Primary Examiner.

W. H. JUST, E. M. COMBS, Assistant Examiners.

1. IN A PUNCH PRESS FOR PRECISION FORMING OF CORRUGATIONS SUCCESSIVELYONE AT A TIME IN METALLIC RIBBON, THE COMBINATION OF OPPOSING DIE MEANSRESPECTIVELY COMPRISING YIELDABLY EXTENDED DIE PORTIONS FOR BRAKING ANDFORMING A FIRST UNFORMED PORTION OF THE RIBBON THEREBETWEEN THEREBY TOFORM ONLY A FIRST PORTION OF A CORRUGATION IN THE RIBBON AS ONE OF THEDIE PORTIONS MOVES YIELDABLY TO BOTTOM ON ITS DIE MEANS AND FOR BRAKINGAND FORMING A SECOND UNFORMED PORTION OF THE RIBBON THEREBY TO FORM ONLYTHE REMAINING PORTION OF SAID CORRUGATION AS THE OTHER DIE PORTION MOVESYIELDABLY TO BOTTOM ON ITS DIE MEANS.